As the moving image distribution protocol, which has been internationally standardized and usable for the moving image distribution through the Internet, MPEG-DASH (Moving Picture Experts Group-Dynamic Adaptive Streaming over HTTP, hereinafter referred to as DASH) which employs HTTP similar to the protocol used for browsing the websites has been known (for example, see Non-Patent Document 1).
In DASH, the adaptive streaming technique has been realized. In other words, on the content supply side, a plurality of streams with the same content but various image qualities and viewing-angle sizes can be prepared in accordance with the communication environment of the Internet or the capability or state on the reception side; on the reception side, the optimum stream can be selected, acquired, and reproduced in accordance with the communication environment of the Internet or the capability or state on the reception side.
In DASH, for allowing the reception side to acquire the stream adaptively, the supply side supplies the meta file called MPD (Media Presentation Description) to the reception side. In MPD, the address (url information) of the chunked streaming data (media data such as Audio/Video/Subtitle) is described, and the reception side can acquire and reproduce the streaming data to be subjected to the HTTP distribution by accessing a predetermined server based on the url information.
FIG. 1 illustrates an example of a configuration of a content supply system 10 that distributes the stream of the content based on DASH.
A content management server 11 on the supply side manages the content to be supplied to the reception side, generates a plurality of pieces of streaming data with different bit rates from the data of the same content, and outputs the data to a DASH segment streamer 12. The DASH segment streamer 12 divides each piece of streaming data of the content into segments temporally to make each into a file, and notifies the address of the file to a DASH MPD server 13. Upon a request from a DASH client 17 on the reception side, the DASH segment streamer 12 serves as the HTTP server to distribute the files of the segmented streaming data by HTTP.
The DASH MPD server 13 generates MPD in which the address of the file of the segmented streaming data and the like are described. Upon a request from the DASH client 17 on the reception side, the DASH MPD server 13 serves as the HTTP server to distribute MPD by HTTP.
A cache server 15 on the Internet caches MPD distributed by HTTP or the file of the segmented streaming data upon a request from a DASH client 17-1. When a DASH client 17-2 requests the cached MPD or the file of the segmented streaming data from the DASH MPD server 13 or the DASH segment streamer 12, the cache server 15 distributes by HTTP the cached MPD or the segmented streaming data to the DASH client 17-2 instead of the DASH MPD server 13 or the DASH segment streamer 12.